Author Contributions: Dr Chen had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. Drs Sheets, Goldin, and Meyer contributed equally to this article.
Study concept and design: Sheets, Goldin, Meyer, Holmes, Godley, Carpenter, Chen.
Acquisition of data: Goldin, Carpenter, Chen.
Analysis and interpretation of data: Sheets, Goldin, Meyer, Wu, Chang, Stürmer, Reeve, Godley, Carpenter, Chen.
Drafting of the manuscript: Sheets, Goldin, Meyer, Carpenter, Chen.
Critical revision of the manuscript for important intellectual content: Sheets, Goldin, Wu, Chang, Stürmer, Holmes, Reeve, Godley, Carpenter, Chen.
Statistical analysis: Meyer, Wu, Chang, Holmes, Reeve, Chen.
Obtained funding: Meyer, Godley, Carpenter, Chen.
Administrative, technical, or material support: Stürmer, Carpenter, Chen.
Study supervision: Godley, Chen.
Conflict of Interest Disclosures: All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Stürmer reports receiving investigator-initiated research funding and support as principal investigator (RO1 AG023178) and coinvestigator (RO1 AG018833) from the National Institute on Aging at the National Institutes of Health (NIH), funding as principal investigator of the University of North Carolina (UNC) Developing Evidence to Inform Decisions about Effectiveness (DEcIDE) center from the Agency for Healthcare Research and Quality, salary support from the UNC Center of Excellence in Pharmacoepidemiology and Public Health, consultancy on the Genentech CER advisory board, and from unrestricted research grants from Merck and sanofi-aventis to the UNC. Dr Godley reports receiving compensation for participating in the data and safety monitoring committee for Ferring Pharmaceuticals, which manufactures Degarelix, a hormonal treatment for prostate cancer that is not directly related to the subject of this study, and receiving compensation for consultancy with GlaxoSmithKline. No other disclosures were reported.
Funding/Support: This research was funded by the Agency for Healthcare Research and Quality, US Department of Health and Human Services as part of the DEcIDE program, contract HHSA290-2005-0040-I-TO6. This publication was made possible by grant 2T32NR008856 from the National Institute of Nursing Research (NINR) at the NIH.
Role of the Sponsor: The sponsor was involved in the review and approval of the manuscript; however, the sponsor did not participate in the design and conduct of the study; in the collection, analysis, and interpretation of the data; or in the preparation of the manuscript.
Disclaimer: This study used the linked Surveillance, Epidemiology, and End Results (SEER)–Medicare database. The interpretation and reporting of these data are the sole responsibility of the authors. This article's contents are solely the responsibility of the authors and do not necessarily represent the official views of NINR.
Previous Presentations: Presented at the American Society for Radiation Oncology Annual Meeting, Miami, Florida, October 4, 2011; and the Genitourinary Cancers Symposium, San Francisco, California, February 2, 2012.
Additional Contributions: We thank Tzy-Mey Kuo, MPH, PhD (University of North Carolina at Chapel Hill), Jane Darter, BS (University of North Carolina at Chapel Hill), Seth Tyree, MS (University of North Carolina at Chapel Hill), and Laura Hendrix, MS (University of North Carolina at Chapel Hill), for technical assistance; William Lawrence, MD, MS (Agency for Healthcare Research and Quality), for assistance with the study and manuscript; Centers for Medicare & Medicaid Services and the SEER program tumor registries in the creation of the SEER-Medicare database; and M. Alan Brookhart, PhD (University of North Carolina at Chapel Hill) for his assistance with the instrumental variable analysis. Work on this study was supported by the Integrated Cancer Information and Surveillance System, UNC Lineberger Comprehensive Cancer Center, with funding provided by the University Cancer Research Fund via the state of North Carolina. No one received any additional compensation beyond usual salary for his or her contributions.